Vascular endothelial growth factor-a and islet vascularization are necessary in developing, but not adult, pancreatic islets.

Reinert RB, Brissova M, Shostak A, Pan FC, Poffenberger G, Cai Q, Hundemer GL, Kantz J, Thompson CS, Dai C, McGuinness OP, Powers AC
Diabetes. 2013 62 (12): 4154-64

PMID: 23884891 · PMCID: PMC3837071 · DOI:10.2337/db13-0071

Pancreatic islets are highly vascularized mini-organs, and vascular endothelial growth factor (VEGF)-A is a critical factor in the development of islet vascularization. To investigate the role of VEGF-A and endothelial cells (ECs) in adult islets, we used complementary genetic approaches to temporally inactivate VEGF-A in developing mouse pancreatic and islet progenitor cells or in adult β-cells. Inactivation of VEGF-A early in development dramatically reduced pancreatic and islet vascularization, leading to reduced β-cell proliferation in both developing and adult islets and, ultimately, reduced β-cell mass and impaired glucose clearance. When VEGF-A was inactivated in adult β-cells, islet vascularization was reduced twofold. Surprisingly, even after 3 months of reduced islet vascularization, islet architecture and β-cell gene expression, mass, and function were preserved with only a minimal abnormality in glucose clearance. These data show that normal pancreatic VEGF-A expression is critical for the recruitment of ECs and the subsequent stimulation of endocrine cell proliferation during islet development. In contrast, although VEGF-A is required for maintaining the specialized vasculature observed in normal adult islets, adult β-cells can adapt and survive long-term reductions in islet vascularity. These results indicate that VEGF-A and islet vascularization have a lesser role in adult islet function and β-cell mass.

MeSH Terms (9)

Animals Cell Proliferation Endothelial Cells Glucose Insulin-Secreting Cells Islets of Langerhans Mice Neovascularization, Physiologic Vascular Endothelial Growth Factor A

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